Engine/Transmission (1994 - 1998) 3GSK and 4GSK

[Tom C]

I know this has probably been asked but I could not find a answer by searching the archives.



What is the anvantage of installing a 3 or 4GSK???



When I had my '97 these parts were not available or too new that no one knew of it. I went to a '01 for a while. did not like the 24 valve motor so Im back to the 12 valve. But now I see every one talking about these 3 and 4GSK. alot has chaged in such a short time.



My truck is pretty much stock (see sig) but it runs super strong. just yesterday I romped on it to get into traffic and in the upper RPMs I looked into the review while my right foot was on the floor and I could not see the car behind me from all the black smoke . It seems to pull good off the bottum but as soon as I get boost out comes the smoke and off I go. In my '97 I had a #12 TST plate and AFC spring kit and I dont think it would keep up with this '95 (sorry Brian I know you've made changes so it would most likely beat me now )



Another question I have is. What would happen if I move the Cam plate forward?



I will probably be adding a #5 TST with the AFC spring kit but I'm waiting to get gages to see how its doing now before I make mods.



I almost forgot. My RPMs will get to 32 to 3300 rpm with ease.



Thanks in advance



Tom C

 

[Joe G.]

Tom,



Your '95 sure doesn't sound like it's "pretty much stock". A stocker defuels at about 2800 or so. Not much smoke if any at all.

 

[Tom C]

Hi Joe, AFC housing still has break off screw and orginal paint intact. It looks like someone has been in the AFC spring access hole on top of AFC housing. I am the second owner. I asked the orginal owner if he had put in injectors (he said no). I asked if he added a cam plate (he asked what a cam plate was). He said the only mod was to the pump. It will pull hard with smoke all the way to govenor cut off (3300 rmp). boost control elbows look stock.



thanks



Tom C

 

[jpearson]

I agree with Joe a stock 95 don't run like that and it sounds like you already have a spring kit.

 

[C Schomer]

See if the wire seal is still on the stamped steel plug on the side of the governor housing. It's below the afc housing under the linkage and it's about 1 1/2" dia. . Craig

 

[Tom C]

I just went out and looked again. this time with a good flash light. I never seen this before but let me know if the manufacturer ever left the head on the break off screw!! I have a prime-lock so its hard to see in that area. the first time I looked I basically saw the break-off screw then looked at its base to see if the paint was disturbed. I never looked at the top of the screw . I remember the original owner telling me he had the mod to the pump done when the truck was a year old. maybe he thought they modified the pump and they really modified the AFC plate and spring... . then repainted it because it would have most likely still have been under warranty. although he said they timed the pump. maybe he had both done



Well I know what my next warm day job will be. A little exploratory surgery



I am still interested in what the 3 and 4GSK springs do. I don't think they were out in '96.



Tom

 

[Tom C]

I went back and looked again. I took along a copy of TSB 14-07-97 for help on were to look. Its hard to see in those spots. But I found there are NO wire ties on anything! I will open the AFC someday (warm day) to see if the plate has been changed.



I need to add some gages. I was in Tulsa yesterday. If I had thought of it I could have had it Dyno'd.



How do you tell the diiference between a 175 HP pump and 225 HP pump?



thanks again



Tom

 

[Joe G.]

Tom,



A plate kit comes with a replacement break off screw. Also look at your boost elbow. If it has a set screw you probably have a plate in it.

 

[Tom C]

Joe, There is no set screw in the eblow. paint is disturbed on the elbow, AFC spring access cap and the injector lines at the pump side and injector side. all other areas appear to be untouched. Im thinking some one has been in there with a can of paint when originally modified.



Tom

 

[Joe G.]

Sometimes the boost elbow is just plugged. It sounds like it runs like it has a #5 plate in it. If it get on mine it would smoke like a forest fire before I advanced the timing. It still smokes but not quite as bad. I have some 370 injectors I haven't got around to installing yet. When I do that I will attempt to adjust the AFC so it doesn't kill so many skeeters.



Another thing you want to check is the valve springs. '95s were stock with 35 lb springs. 60 lb springs are very slightly barrel shaped and have a stripe on them.

 

[C Schomer]

I have yet to find "shake n shoot" paint to match but it sounds like your pump is really worked over. There are wire seals on the "zero air" screw - pointing straight back on the back of the afc, also on the rectangular cover below the afc on the back of the gov. housing (entry point for Piers rocker adj. ) and the round plug on the lt. side of gov. (can be entry point for gov. spring kit). I have the 3k kit. It made for strong low end fueling and pulls past 3k but the strongest change was low and mid range. My 97/215 is cpl 2175 - it's stamped on the engine tag ahead of the injector pump. You really need gauges! Is the exhaust stock - 3" w/cat? It's harder to tell about the turbo but if it's wastegated, it's a 12 or 14. Probably a 12 or the origonal owner should have known. I'm guessing the stock plate is slid forward or the first owner should have known if it were aftermarket. I'm assuming his mechanic and he aren't keeping any secrets - it sounds like they aren't. Craig

I read your first post again. I was thinking you had a 97 now. You won't have cpl 2175, sorry.

 

[Joe G.]

Believe it or not, you can buy the exact color from Cummins.



When I had the stock plate pushed forward on my '95 it smoked but not bad.



If the engine still has stock valve springs it is supposed to have problems with valve float above 3200. I dunno about that for sure, but that's what I have read. I suspect that the valve springs have been replaced with 60lb springs on this one.



People tend to tell stories when they sell a vehicle. So I would check injectors and whatever else comes to mind before making any changes.

 

[Tom C]

Schomer, No wire ties, all gone. Exhaust is stock less the muffler. I dont think the exhaust valve springs were changed. I'm planning on putting in the #60 for better exhaust braking. How do I put them in without taking the head off?



Joe, Your right about the stories. The owner told me that the tach would hit the red fast, to watch it. When I test drove the truck it was wet, raining, school zone or slow city streets. I did not test drive on the hwy. . It seemed to run good. the next day I came back with cash and left. when I went to get on the highway a semi was leaving me in the dust . I could not get the rpm's past 2400. I thought 'ye right' on the fast red lining rpm's. turns out the metal boost hose to the turbo was worn through (the owner must not have had any top end for 6 months to a year). I replace the hose and she runs much better than I anticipated. I bet the guy even brought it to the dealer to find the problem and they missed it. They probably told him it needed a pump. So he put it up for sale and ordered a 2003 1 ton single wheel.



So the 3GSK will help low rpm power (before boost)??? If so it may be worth it.



Tom

 

[C Schomer]

More fuel from off idle on up! I have the zero air and afc adjusted pretty good but still have to watch my right foot to stop all the smoke and get the best city mpg. I adjusted my zero air screw - preboost smoke was DARK. I got SO much better low and mid power, I thought something happened to hurt the top end - it wasn't a proportionate increase but known test hills proved I had a bit more power on top end too besides more rpm. Top end wasn't such a wild increase until I fixed the plate. The GSKs will allow more rpm but the amount of top end power and actual rpm limit still depends on if you can squirt enough fuel. Some guys get 3500rpm or so out of a 3k kit. I don't know if your 180 fueling will be the weak link but I can get more than enough fuel out of my 215 for any rpm or egt I want to hit - up to about 3200 rpm. Craig



Joe, thanks for the tip. I think I've tried Cummins but I'll try harder next time.

 

[Deezul1]

I betcha it has a 3K GSK in it as 2800-2900 is all either one of my 12 valves would go flat out when stock. I have the 4k GSK and dont float valves till about 3700 rpm with stock springs.

 

[Tom C]

Well, I finally got to explore in the AFC housing. All parts appear to be stock. The fuel plate is full forward and the AFC spring appears to have been adjusted.



I also installed an EGT/Boost gage. In second gear with the right pedal on the floor, EGT went to 1400°, boost at 30PSI and rpm went to 3400. In 3rd gear, boost was about 25PSI, and rpm got to about 3200 when I noticed the EGT pegged the gage (about 1550°). Seems I need to slide my fuel plate back a little



The EGT did not hit danger zone until rpm's were next to red line.



I dont know what the 0-60 or 1/4 mile times are but I bet not bad for a stock truck with a little screw driver work although I dont know exactly what pump mods were made.



next on the list is to install a fuel pressure gage. then a #5 plate, 3GSK and AFC spring kit.

 

[Got Smoke?]

Originally posted by Tom C

next on the list is to install a fuel pressure gage. then a #5 plate, 3GSK and AFC spring kit.

Hope you have some transmission work done before that plate goes in!



I'm ordering my clutch Friday so I can get my #10 soon! Oo.

 

[Tom C]

Got Smoke,



If the clutch slips after the mods, then I guess I get a new clutch



What kind of clutch are u putting in?

 

[Got Smoke?]

Originally posted by Tom C

Got Smoke,



If the clutch slips after the mods, then I guess I get a new clutch



What kind of clutch are u putting in?

Tom couldn't see what kind of transmission you had since you must have posted on the first page. I was planning on going with a SBC OFE, but I am on a budget so I'm going to go with a TST Clutch. Rob Thomas and Gizmoo 007 both said they will hold 450HP and I will only ever see 400 (and not for a while at that) so I'm going to use the extra $$ I save to order a #10 plate.